The present invention relates to a data reproduction method and a data reproduction apparatus.
Widely used DVD may be a reproduction-dedicated medium DVD-ROM or recording type DVD (DVD-R, DVD-RAM, DVD-RW, etc.) A DVD-ROM containing a content such a movie is manufactured using the copyright protection technique CSS (Content Scramble System) for limiting copying.
As a copyright protection technique other than the CSS, there are CPPM (Content Protection for Prerecorded media) and CPRM (Content Protection for Recordable Media). Thus, an optical disc such as DVD employs a copyright protection technique in accordance with the recording medium.
Moreover, JP-A-2005-182889 discloses a copyright protection technique for an information recording medium. JP-A-2005-182889 introduced a method using a physical index for performing content reproduction.
Furthermore JP-A-2002-158978 discloses an electronic watermark embedding method and a detection method for changing the embedding intensity.